Industrial Valves

8Safety Valves

8.1 Introduction

Pressure safety valves (PSVs) and pressure relief valves (PRVs) are collectively referred to as safety valves, which are used in all pressurized equipment and facilities such as piping, pumps, compressors, turbines, and boilers when overpressurizing can occur. The principles of protection from overpressurizing are briefly presented in Chapter 2. In addition, the sizing of safety valves is covered in full detail in Chapter 2. The objective of this chapter is to provide an overview of essential design considerations and calculations for PSVs and PRVs, including the relief of pressure and capacity as well as generating reaction forces. There is a noticeable sound made by these valves during operation, which can be measured using the methods and calculations described in Chapter 6. For whatever reason, if something goes wrong with the pressure piping or equipment which leads to overpressure scenarios, the excessive pressure can damage or burst the expensive equipment and piping. PRVs and PSVs are installed over pipes and equipment to prevent undesirable events and enhance safety and reliability. If the pressure inside the equipment or piping exceeds the allowable limit, the safety valve automatically opens and releases the extra pressure. The result is a reduction in pressure across the protected equipment or piping. Both PSVs and PRVs are sometimes referred to as spring valves. There are two main differences between a PSV and a PRV; the first is ...